Rotary engine.



W; M. HOFFMAN-n ROTARY ENGINE.

- APPLICATION FILED JUNE 1, 1909. 985,04, Patented Mar. 7. 1911.

2 BEBETBSHEET 1.

W. M. HOFFMAN.

ROTARY ENGINE. APPLIOATION FILED JUNE 1, 19091 Patented Mar.7, 1911.

2 SHEETS-SHEET 2.

EINETE 'i TATES PATENT FFTQE.

WILLIAM M. HOFFMAN, OF BUFFALO, NEW YORK, ASSIGNOR TO THE HOFFMAN PATENTS, LIMITED, A CORPORATION OF CANADA.

ROTARY ENGINE.

To all whom it may concern:

Be it known that I, lVILLiAM M. Horr- MAN, a. citizen of the United States, residing at Buffalo, in the county of Erie and State of New York, have invented a new and useful Improvement in Rotary Engines, of which the following is a specification.

This invention relates to rotary steam engines of that type having a rotary cylinder, a core or part which rotates with the cylinder and is ar 'anged eccentrically in the cylinder in contact therewith at one side so as to form a crescent-shaped piston chamber, and one or more pistons or blades which bridge the piston chamber and against which the steam or other motive fluid acts to drive the engine.

One object of the invention is to produce an efficient compound engine of this type which is of simple construction and in which the low pressure cylinder, which is of larger diameter than the high pressure cylinder, surrounds or incloses the latter. The steam pressure in the piston chamber between the cylinder and core tends to separate these parts, or force them apart in opposite directions, thus causing excessive pressure on their bearings.

Another object of this invention is to construct the engine so as to equalize or balance this pressure on the bearings, thereby reducing the friction and consequent wear in the bearings, and increasing the efficiency of the engine.

In the accompanying drawings. consisting of two sheets: Figure 1 is a longitudinal sectional elevation of a rotary engine embodying the invention, in line 11, Fig. 2. Fig. 2 is a transverse sectional elevation thereof in line 22, Fig. 1. Fig. 3 is a fragmentary longitudinal sectional elevation thereof in line 3-3, Fig. 2. Figs. i and 5 are transverse sectional elevations thereof in lines 4:-4r and 55, respectively, Fig. 1. Fig. 6 is a transverse sectional elevation thereof in line 66, Fig. 1.

Like reference characters refer to like parts in the several figures.

A represents the rotary cylinder which is journaled at its opposite ends on bearings b which are preferably formed on the opposite ends of a stationary casing B inclosing the cylinder. The cylinder has an inner cylindrical wall a located concentrically within its outer cylindrical wall a and joined to the Specification of Letters Patent.

Application filed June 1, 1909.

Patented Mar. 7, 1911.

Serial No. 499,395.

latter by a wall or partition 64 which is arranged centrally between the ends of the cylinder and divides the latter into two compartments. The outer and inner cylindrical walls a and a and partition (4 are conveniently made integral.

C and C represent two annular cores or piston carriers which are arranged eccentrically within the two compartments of the cylinder around the inner wall (4 thereof, so that the cores contact at one side thereof with the outer wall (1 of the cylinder and at the opposite side thereof with the inner wall a of the cylinder. Each core thus divides the compartment in which it is located into an inner high pressure piston chamber 1 within the core and an outer low pressure piston chamber 2 surrounding the core. The annular cores are joined by end walls 0 to hubs c keyed or otherwise secured to a drive shaft D which is journaled in the bearing 6 eccentrically to the cylinder A and is turned by the cores.

E and E represent high pressure pistons or blades which are arranged in the two inner piston chambers, and F and F represent low pressure pistons or blades which are arranged in the two outer piston chambers. The pistons E and F are pivoted at one end in any suitable manner at diametrically opposite points to the core C, and the former piston extends across the high pressure chamber 1 and bears at its free end on the inner wall a of the cylinder, while the latter piston, F, extends across the low pressure piston chamber 2 and bears at its free end against the outer wall a of the cylinder. The core is provided with pockets into which the pistons are adapted to swing. The other pistons E and F are similarly pivoted to the other core C and arranged respectively in the high pressure and low pressure piston chambers formed by this core C, but the high pressure piston E is arranged diametrically opposite to the other high pressure piston E, and the low pressure piston F is diametrically opposite to the other low pressure piston F. The steam or other motivc fluid isadmitted first to the two high pressure piston chambers 1 behind the pistons E and E and acting thereon drives the engine in the direction indicated by the arrows, the steam in front of the high pres sure pistons exhausting from the high pressure chambers 1 into the low pressure piston chambers 2 inrear of the low pressure pistons F and F so as to act by expanslon thereon and assist in driving the engine.

In the construction shown, the drive shaft D is made hollow at one end or provided with an inlet passage G which connects at its outer end with a steam chest 9 through which the shaft passes, and at its inner end by a port 9 through the hub of the core C, with the chamber or space between the hubs of the core and the inner wall a of the cylinder. The steam passes from this space 9 by ports h h, Figs. 2 and 8, in the walls of the cores 0 and G, into the high pressure chambers 1 in rear of the pistons E and E therein. The steam in front of the high pressure pistons passes from the high pressure piston chambers through passages 2' and 71, Figs. 4t and 5, in the annular cores C and C, respectively, into the low pressure piston chambers 2 behind the low pressure pistons F and F. The steam exhausts from the low pressure piston chambers 2 in front of the pistons F and F through exhaust ports and 70, respectively, (Figs. 4 and 5) through the outer wall a of the cylinder into the easing B surrounding the cylinder from which the steam discharges through. a suitable exhaust pipe Z. The steam is admitted to act on each piston in each revolution of the engine when the piston passes the abutment or point of contact between its core and the wall of the cylinder, and as soon as the exhaust passage for each piston passes the abutment the steam can exhaust therethrough from in front of the piston. Valves will ordinarily be employed for timing the admission and cut oi the steam, but the invention is not concerned with the valve arrangement and this is not shown. The pressure of the piston E by the steam on the inner cylinder wall a and that of the piston F on the outer cylinder wall a is substantially in the same direction, that is, downwardly in the position of the parts shown in Figs. at and 5, which tends to force the cylinder downwardly and lift the core O to which the pistons are pivoted. At the same time the pressure of the other pistons E and F respectively on the inner and outer cylinder walls is in the opposite direction, or upwardly in the position of the parts shown in Figs. 4 and 5, which tends to force the core O downwardly and lift the cylinder. Thus the pressures in the two cylinder compartments act oppositely and tend to equalize or balance the pressures on the bearings for the cylinder and cores. As the cores, cylinder and pistons all travel in the same direction, the only movement of the pistons on the cylinder is that due to the slip or relative motion in-the same direction between the cores and cylinder on account of their eccentric arrangement, and consequently the friction and wear on the pistons and cylinder produced by the sliding of the one on the other is not great.

The cylinder and cores may be caused to turn in synchronism in the same direction by any suitable means. The means shown consist of yokes or boxes M, Figs. 1 and 6, which have arms at slidably engaged in guide-ways 772 formed in the end walls of the cylinder which permit the boxes to slide in one direction, and blocks m keyed to the drive shaft are arranged to slide in the boxes M in a direction at right angles to the direction of movement of the boxes in the cylinder. These boxes and bloc is cause the cylinder and cores to turn together in the same direction but permit the necessary rela tive movement of the cores and cylinder due to their eccentric arrangement relative to ach other.

The joints between the parts of the engine are suitably packed wherever necessary, but the packing means do not constitute a part of the invention and are not shown in the drawings.

I claim as my invention:

1. In a rotary engine, the combination of a rotary cylinder having inner and outer cylindrical walls, an annular core which rotates in the same direction as the cylinder and is arranged eccentrically therein and forms with the inner cylinder wall a high pressure piston chamber and with the outer cylinder wall a low pressure piston chamber, a piston connected internally to said core and bearing on the inner cylinder wall, a piston connected externally to the core and bearing on the outer cylinder wall, means for admitting motive fluid inside of the inner cylindrical wall of said cylinder, passages in said core for admitting the motive fluid from said cylinder to said high pressure chamber and then to said low pressure chamber, and exhaust ports in said outer cylindrical wall of said cylinder, substantially as set forth.

2. In a rotary engine, the combination of a rotary cylinder divided longitudinally into two compartments, cores which are arranged cccentrically in said compartments and rotate in the same direction as the cylinder, pistons in said two compartments between said cores and the cylinder and on which the motive fluid exerts pressure in opposite directions, and means for admitting motive fluid to and exhausting it from the cylinder, substantially as set forth.

3. In a rotary engine, the combination of a rotary cylinder divided longitudinally into two compartments and having inner and outer cylindrical walls for each compartment. an annular core which is arranged eccentrically in each compartment and forms with the inner and outer cylindrical walls inner and outer piston chambers, a piston in the outer piston chamber of one compartment, a piston in the inner piston chamber of the other compartment, and means for admitting motive fluid to and exhausting it from said piston chambers, substantially as set forth.

at. In a rotary engine, the combination of a rotary cylinder divided longitudinally into two compartments and having inner and outer cylindrical walls for each compartment, an annular core which is arranged eccentrically in each compartment and forms with the inner and outer cylinder walls inner and outer piston chambers, pistons in the inner and outer piston chambers of each compartment, and means for admitting motive fluid to and exhausting it from said piston chambers, substantially as set forth.

5. In a rotary engine, the combination of a rotary cylinder divided longitudinally into two compartments and having inner and outer cylindrical walls for each compartment, an annular core which is arranged eccentrically in each compartment and forms with the inner and outer cylinder Walls inner and outer piston chambers, pistons arranged diametrically opposite to each other in the inner and outer piston chambers of each compartment, the pistons in the corresponding piston chambers of the two compartments being at opposite sides of the engine, and means for admitting motive fluid to and exhausting it from said piston chambers, substantially as set forth.

6. In a rotary engine, the combination of a rotary cylinder divided longitudinally into two compartments and having inner and outer cylindrical walls for each compartment, an annular core which is arranged eccentrically in each compartment and forms with the inner and outer cylinder walls inner and outer piston chambers, pistons in the inner and outer piston chambers of each compartment, means for admitting motive fluid inside of the inner cylindrical wall of said cylinder, passages in said cores for admitting the motive fluid from said cylinder to said inner and then. to said outer piston chambers, and exhaust ports in said outer cylindrical wall of said cylinder, substantially as set forth.

\Vitness my hand, this 28th day of May,

W'ILLIAH M. HOFFMAN. Vitnesses G. B. HoRNBnoK, C. WV. PARKER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

